Calibration Method for Reducing Ring Artifacts in Energy Bin Images for Photon-Counting CT

Area of Science:

• Medical Imaging
• Detector Physics

Background:

• Pixel-to-pixel variation in photon-counting detectors (PCDs) is a major challenge in computed tomography (CT) imaging.
• This variation leads to artifacts such as rings, degrading image quality.

Purpose of the Study:

• To develop and validate a novel calibration framework to address pixel-to-pixel variation in PCD CT imaging.
• To reduce ring artifacts and improve quantitative accuracy in CT images.

Main Methods:

• A streamlined data acquisition strategy using calibration phantoms for comprehensive pixel-level thickness data.
• Three dedicated calibration steps generating correction coefficient tables for pixel variation and count-rate non-linearity.
• Experimental validation on a prototype PCD-based CT system using radial mean standard deviations (RMSDs) for artifact evaluation.

Main Results:

• The proposed calibration method achieved significant reductions in high-frequency RMSDs (95.7% for total counts, 93.6% for energy bins).
• Substantial improvements were observed in low-frequency RMSDs (97.2% for total counts, 55.7% for energy bins).
• The novel approach outperformed conventional calibration methods in artifact reduction.

Conclusions:

• The developed calibration framework effectively addresses pixel-to-pixel variation in PCDs.
• This method offers a promising solution for enhancing CT image quality and reducing artifacts in PCD systems.